Coatings are provided in which surfaces may be activated by covalently bonding a combination of silane derivatives (A) to the metal surface, covalently bonding a lactone polymer (B) to the silane derivative by in situ ring opening polymerization, and depositing at least one layer of a polyester (C) on the bonded lactone polymer. Biologically active agents or therapeutic compounds may be deposited with any of the polyester layers. Such coated surfaces may be useful in medical devices, in particular stents.